dieseldiehard: "Atomic core" should be "atomic nucleus".

P.E.Haiges: Evans waterless coolant requires a near complete removal of all water in the cooling system. Doing this on an old Mercedes would be quite a big chore and may be very time-consuming (several days to dry with a hair dryer etc..)

In pure water, the following 2 reactions constantly occur in both directions, and they are in an equilibrium state.

1) H20 <-> H(+) + OH(-)

2) H2O + H20 < -> H3O(+) + OH(-)


H(+) is a positive hydrogen ion, OH(-) is a negative hydroxide ion, and H3O(+) is a positive hydronium ion.

In tap water, the existence of minerals (and salts) such as NaCl, KCl, Na2CO3, NaHCO3, NaNO3, CaCO3, MgCO3 etc... means that there is an abundance of other ions such as Na(+), Ca(2+), Mg(2+), Cl(-), CO3(-2), NO3(-) .... besides the above-mentioned water-derived ions.

We generally have 3 different terms for "purified water".

1) De-mineralized water (pure), also called "softened water"

2) Distilled water (purer)

3) Deionized water (purest)


Deionized water, de-mineralized water, distilled water are called "purified water" because the extra minerals and salt ions are removed thanks to chemical precipitation/resin ion exchanges, and steam distillation/condensation (for distilled water only). So most of the extra ions (besides the water-derived ions) are extracted, but the water-derived ions (hydrogen ions, hydroxide ions, hydronium ions) are always there, because that's how water molecules and their ions exist in constant equilibrium.

In a nutshell, the strength of an acid is represented by the concentration of hydrogen ions H(+) it can create, and the strength of a base (alkaline) by the concentration of hydroxide ions (OH-).

The pH of a solution is calculated from the formula: pH = -log[H+]
Remember that this "log" stands for decimal logarithm (base 10), not the natural (or Napierian) logarithm (base e=2.7182818..)

For the purest water, the concentrations of H(+), OH(-), H3O(+)
are equal, so [H(+)] = [OH(-)] = [H3O(+)] = 10^(-7). Therefore, the pH of purest water is:

pH = -log[H+] = -log(10^-7) = - (-7)log(10) = 7x1 = 7

For real acids, [H+] is definitely greater than 10^(-7), i.e. it should
be 10^(-n) where n < 7. This means that the pH of an acid is always less than 7:

pH = -log[H+] = -log(10^-n) = -(-n)log(10) = nx1 = n < 7


For real bases, [H+] is less than 10^(-7), i.e. it should be 10^(-m) where m > 7. This means that the pH of an acid is always greater than 7:

pH = -log[H+] = -log(10^-m) = -(-m)log(10) = mx1 = m > 7


For tap water (H+, OH-, H30+, Na+, Cl-, NO3-, etc....), the mineral or salt ions react with water-derived H+, H30(+) ions and prevent them from acting like an acid (which are very corrosive to metals). De-mineralized/deionized/distilled water don't have or have very little mineral/salt ions, so the water-derived H+, H3O(+) are free to attack metal atoms by sucking the low valence electrons from the outer orbital shell of metal atoms (note that H+ and H3O+ have positive charge and electrons have negative charge, so they have high affinity for each other)

The chemical ingredients in the antifreeze coolants such as Dexcool and Mercedes/Zerex G-05 produce lots of other ions that help neutralize the effect of H+, H3O(+) in de mineralized/deionized/distiller water (purified water), so it is OK to mix purified water with antifreeze without any problem. Keep in mind that you MUST use at least 50% antifreeze in your antifreeze/water solution (but less than 70%)! If you follow the proper mixture ratio, purified water is always better than tap water. No minerals/salts = No scaling/deposits/blocking...

HOWEVER, if you use too little antifreeze or just simply use purified water in your cooling system (such as in racing cars), you will kill your engine/radiator IN NO TIME FLAT because of the attacking H+, H3O+ from purified water.

Eric